It seems that most adults who have completed their secondary education take
the constructs of physics to be the material or magical "causes" of natural
phenomena. Such an assumption is questionable, both epistemologically and
pedagogically, and if we want to prevent this kind of error from
continuing, it won't be enough to try to protect a few high school seniors.
The only thing that will be effective in all types of schools is, from the
outset, to follow a basic principle and adhere to it strictly:
understanding needs grounding in the phenomena.

It is easy to see that only a very small percentage of physics
students - five out of a hundred perhaps - have ever seen a planet in the sky
or followed its course. I mean: the very thing, with the naked eye,
outside. Nobody was there to point to the actual planet. This is a
remarkable finding when one considers how the planets stood around the
cradle of physics during its infancy in the sixteenth and seventeenth
centuries.

Physics without an Ear for Sound

I'm convinced that the loss - or disappearance - of freely observed natural
phenomena in the physics classrooms of our secondary schools and colleges
is not merely a discarding of semblance and show. It implies that we
disrespect our own foundations and those of natural science. In doing so we
put our educational success at risk. We may lose our trustworthiness and
credibility.

We risk getting caught in a common and old methodological temptation. Two
hundred years ago, Pestalozzi - thirty-six years old at the time - wrote about
it in a letter: "Schools bring judgments before people see and get to know
things for themselves..." [i]

This can easily lead students to become prejudiced with the old argument
about what has primacy: the things themselves (the first appearance, the
phenomenal reality) or what we think about them, and over
and above them, which means the mindscape of physics.

From early on the accusation was leveled against physics that it was out
to spoil our faith in the senses. It is noticeable that this opinion is
also not rare today. When one impresses on someone that "music is really
nothing more than vibrations in the air, warmth as such only movement of
molecules, color in fact nothing but electromagnetic wavelength," it will
often happen that the person addressed will nod in agreement, albeit
somberly.

Let's listen to a group of nine-year-old boys in the laboratory school of
the University of Tübingen. They have a teacher who tells them little (he
doesn't talk them into anything) and has taught them to talk with one
another and to stick to the point, to say everything they think, but also
to think about what they say. For hours they discuss why the sound of a
distant jack hammer or of a drum lags so much behind the sighting of the
movement. They check the skin of the drum with their eyes, fingers and
tongues, they make their observations and say (according to the tape), "it
hops and trembles, it trembles and tickles, it almost burns" (on the
tongue). At last they conclude: arriving later is due to the air. Air
"carries" the sound to us, and that takes time. And how does it "carry"?
Their conclusion after a long conversation and experiments: when I beat
against the drum skin, it wobbles and the air is pushed away. The air
wobbles back and forth, and that air pushes the other air, and the
air next to it, and so on. That way it wobbles through the air until it
reaches my ear.

At a later point, these children will learn to record the wobbling at a
place between drum and ear by means of a mechanical sound receiver. The
results, then, will be something like the "air pressure curve." What have
they, and we, gained through such a curve? The answer may be obvious, but
strangely enough I have not found it in any textbook, namely: we have
gained exactly what remains of the sound for someone who cannot hear.

Now if a teacher would say about this curve, "you see, the sound is in
reality nothing but this vibration in the air," it would be absurd. Because
why should the ear be singled out to be less relevant to record the reality
of sound than the other, less appropriate senses? I'm not saying that
teachers actually put such a "nothing but" expression in words. But what I
miss is textbooks expressly denying this. The "nothing but" attitude seems
to be in the air; it is between the lines. It is as if it were being
learned along the way.

The teacher can, and should at this point, only pronounce the true state
of affairs, namely that people in physics have decided to concern
themselves only with the mechanical aspect, which is the air pressure
curve. Hence "physical acoustics" only contains what remains of sound, and
of music, for someone who is deaf.

And of course teachers should also make conscious what has prompted this
decision to proceed in this way: air pressure can be measured, but the
immediate experience of sound cannot. In this way the teacher can prepare
the students for a fundamental insight, which is that physics is a
self-limiting science, an intelligently renouncing science.

Above all, two things should be taken into consideration. In reducing
ourselves to what can be measured, we cannot bypass the senses. We
estimate and measure with hands and eyes, and the whole body; we measure
distance, time span, and muscle force. Secondly,
we must be clear about the fact that reducing the sound we hear to the
air pressure curve is a one- way street. There is no way we can ever
fully convey to someone who doesn't hear what a tone, a singing voice,
or a gong sounds like. We can only give an indication in words.

When the teacher teaching acoustics allows the nine-year-olds to
critically ponder the "wobbling" of the air in the way described above, and
sticks to this way of teaching, he can keep them open for what they will
later learn or read about modern physics, which is the following.

Physics is, according to the opinion of leading modern researchers, only
one - albeit also the most powerful - of possible views of nature. It is not
free from assumptions, but limits itself right from the start to what can
be measured with yardstick, scale, and clock, insofar as we can bring the
data thus measured into relationship with one another and coordinate them
in mathematical structures. This results in a specific "picture of nature,"
or, as we could also say, a mindscape. [ii]

According to comparisons stemming from physicists themselves, physics
gives us a picture of the surrounding sensory phenomena in the same way in
which a map pictures a landscape, a score a symphony, or a shadow an
object. In doing so, it gives a picture that is as sharp and correct as the
shadow that a flowering tree throws on a wall. But of course the tree
itself cannot want to be its shadow. Some of its structure and geometry
remain, but color, smell, three-dimensionality, and the rustling of its
leaves are missing.

The human being, who participates in nature after all, really cannot be
expected to define the question about the "essence" of natural appearances
by rational means, let alone find the answer. It is clear that we are only
able to delineate the answer depending on one particular aspect chosen from
a variety; and every aspect, physics included, imposes limitations as well.
We circle around a mystery. Physics teaching should not favor an a priori
impression that the core of this secret could ever be attained through
physics. Bertrand Russell clearly states to what little degree physics can
be ontology, can break through to the essence of things. He says, "What we
know about the physical world... is much more abstract than was formerly
supposed...Of the laws of these occurrences we know something - just
so much as can be expressed in mathematical formulae - but of their
nature we know nothing." [iii]

The Deep Unrest of Matter

We all experience the phenomenon of warmth when we sit in the sun. For
warmth, the physics approach has found something very remarkable and worth
seeing, namely that everything, be it stone, water, or air, has a constant,
invisible, very fine trembling motion inside, which rises or falls with the
temperature.

Ever since I saw with children this "Brownian movement" of small rutile
crystals [in water] projected onto a screen through a dark-field
microscope, I have been an advocate for disclosing this view of a reeling,
starry sky to all children and to allow them to contemplate this sight
in peace. This must be seen! It is hard to understand that all schools don't
show this fundamental phenomenon to all children, instead of prematurely
talking to them about atoms and electrons. Put them in front of the screen
and say as little as possible. Then they will see something real.

Let us assume the ideal case that they don't "know" anything about
"molecules" yet (or that one could first socratically talk them out of
this belief). In that case the path would be open to a compelling approach
to the notion of discontinuity and to the modern insight that the concepts
won on a larger scale are not sufficient when they are transferred to
a smaller scale. Here we have a first-class phenomenon that motivates
and stimulates. Pressing questions arise: why are the dust particles
in movement? Are they alive? No: simple chunks of soot, segments
of crystal, or drops of fat will do the same, if only they are small
enough. They are "in movement," so they don't move themselves,
there is no "voluntary" movement; the particles do nothing themselves,
they just join in the movement! What drives them? It can only be the
water. But the water is completely quiet, isn't it?

Obviously that is not the case. One can hardly get around the hypothesis
that we must imagine there to be a continuous pushing unrest in the deepest
innards of the water (Philipp Lenard spoke of "tiny wiggling"); it is a
very mysterious stirring, a micro-fever. It never stops, it is always
there, and simply belongs to matter and warmth: it rises and falls with the
temperature.

When we give students time and allow them the freedom to think for
themselves (to which they are entitled), they will find this hypothesis of
perpetual wiggling inappropriate. They would see it as a "perpetuum
mobile," and a real one, one that causes friction! They would argue that
such a wiggling could not last, that it would soon exhaust itself in
friction (warming the water somewhat in the process)! This objection is
compelling, and further forces us to come to a disconcerting conclusion.
Water, the way we got to know it as children when we started to play with
it; water, which ran through our fingers; water, which always became
tranquil of its own accord, however wildly we had stirred it: this very
water we were familiar with we now have to picture differently. Deep
inside, in its tiniest dimensions, it must be very different from the way
it is in a large dimension.

This seems not a bad entry into atomic theory to me. Combined with other
conclusions that can be drawn from chemistry, it will be a fruitful
starting point to build on later. This venture into atomism can stand as a
digression. For my purpose here we don't need molecules at all yet. It is
enough to register the discovery that there is a hidden, haphazard inner
movement, the vehemence of which is bound to the degree of warmth.

Should we at this point resort to the "nothing but" philosophy again,
saying: in reality warmth is nothing but inner movement? [iv] All we can say
is this: increasing experience of warmth always goes together with a
visible increase of inner unrest of the warm body, and the other way
around. Or: the inner movement is what is left of warmth for a person who
cannot feel warmth. Or, more clearly still: this is another case where
physics opts for renunciation. It limits itself to "describing" warmth in
terms which are measurable: movement.

With Brownian movement we approach a boundary. These reeling points of
lights are the last optical reflection we can still glean from the
innermost microscopic world of ordinary matter. According to the surprising
insights of the past 50 years, when we penetrate even deeper,
perceptibility is on principle not to be had when it comes to the processes
that take place in the most minuscule spaces. Heisenberg states: "The atom
is in essence not a material formation in space and time, but only, to a
degree, a symbol, which, when introduced, makes natural laws assume a very
simple form." [v] With this in mind, one cannot get rid of an uneasy feeling
when one leafs through elementary textbooks. I am inclined to agree with
another excellent quantum physicist, Walter Heitler from Zürich. He took
pedagogical questions very seriously, remarking: "We do wrong when we want
to teach young people something they can't possibly understand, or to
misrepresent it in order to make it comprehensible ... I don't believe it
is a good thing to talk about atomic physics and electrons in the upper
elementary school. Every spatial representation of these formations is
simply false." [6] It seems that schools, in their very striving to be
up-to-date, simply are not so when they speak of atoms and electrons as if they
were peas, without mentioning how people came to these ideas. In this way,
schools no longer base themselves on phenomena.

Beyond Mechanism and Magic

The conception of electrons as hard things, only small ones, seems to be
thoroughly entrenched, and this misunderstanding contributes heavily to the
fact that so many laypeople believe in a hard, mechanical world underlying
the phenomena, which are then viewed as "nothing but," with secondary
effects that are "only subjective." We know that it is possible to give
information that allows us to use products that we do not understand:
driving a car, watching television, or using all manner of technical
equipment; using mathematical formulae also belongs in this category. In
many situations we cannot get around this. But a well-rounded education
should not primarily be concerned with this form of "understanding." By
understanding I mean: standing on the phenomena. In other words:
experiencing how physics - and this includes science as a whole - is and
becomes possible.

The use of axioms and deduction does not offer a way out. For
when abstract concepts (in their genesis) have not arisen out of
the phenomena, they will be misunderstood. They will be seen
as objective findings rather than constructs that we have produced,
and they will therefore be taken as either coarse material entities
or as magical ones. Such entities are subsequently believed to be the
ultimate causes behind everything that surrounds us - the ontological
misunderstanding of physics.

I cannot go into all the ramifications of this subject here. I will only
try to give some positive examples of how to make it possible to gain
insight into the inner nature of matter, undreamt of before, staying
completely in the realm of phenomena and without having to talk prematurely
about molecules, atoms, and electrons. Let us start with the first subject,
having to do once again with the "inner unrest" caused by the Brownian
movement. This time not - as presented above - simply prepared by the teacher,
but as a path (a "curriculum," if you will). I shall present a series that
begins with direct experiences, a series set in motion by something
strange:

Observe a stone, a polished metal surface, a still pond, some water in a
glass, or the air of this room - they all make the impression of being
completely at rest. When nothing and nobody interferes and there is no
wind, no warmth, and no impact, you will see a dead, passive scene. With
one exception. The water, given time, will surreptitiously disappear from
the glass; it "evaporates," conquers the space, even though it does so
slowly. Has the air absconded with it, or has it achieved this of its own
accord? Does it want to flee? Well, we can take away the air. Let us put
the glass with the water under a closed bell jar and pump the air out of
the jar. We will experience a surprising eruption: the water, the cold
water, begins to form big bubbles and boils away. So it obviously has only
been waiting to get rid of the weight of the air, it wants to boil. When we
take away the air pressure, we only assist what it wants to do of its own
accord.

Now we know that water can also be brought to boil under the burden of the
air pressure, in defiance of that pressure, namely by heating it up.
Therefore we are allowed to say that it looks as if warmth merely supports
water's inner compulsion to come to a boil. In summary, water, just by
itself, has the tendency to become vapor.

This can stimulate us to look for similar processes. Sugar dissolves by
itself in water. Several liquids layered over one another quietly mix by
themselves over a period of days. We find the same thing with gases.
Lastly, there also is the incredible diffusion of solid materials into one
another. Gold, which has been pressed against lead for years, will
gradually wander by itself in small amounts into the lead. And we will end
this series of observations with the most familiar phenomenon: Air or
vapor - all gases - are always ready to conquer any space open to them, either
an empty one or one that is occupied by another gas. Their aggression is
constant, and where they cannot escape, they press against the wall.

If, by way of culmination, we follow all this with a demonstration of the
Brownian movement, we will perhaps notice how well it fits that the
vehement rubbing and stirring makes all things warmer. The inner stirring
can be reinforced from the outside.

This purely phenomenological sequence could show the following:

1. It is possible to give students insight into profound contexts, even if
they are merely preparatory, without talking about mathematics or
molecules.

2. Already ordinary matter will show a new side, one that is threatening.
We can count ourselves lucky. Beware.

Demonstrations Bright and Weighty

This new side becomes even more compelling when augmented by a second
insight that is also purely built on phenomena. The demonstration is
artificial, but simple to set up. It involves not ordinary matter, as with
the Brownian movement, but matter of a very threatening kind, namely
radioactive materials. Look through an ordinary magnifying glass at a
surface of material that has the special feature of giving off a tiny spark
in the places where one scratches it with a needle. How it does that is a
separate issue, which we do not need to understand here, because we only
use it for the purpose of making a phenomenon appear.

Between the magnifying glass and the surface we hold a tiny bit of radium
salt, applied to a thin wire on the side that faces the surface (the side
away from the eye). The magnifying glass is adjusted to the surface. When
it is pitch dark and your eyes are rested, preferably in the middle of the
night, you will see a sight that is as unforgettable as the Brownian
movement. No whirling stars this time, but stars that light up and
disappear again in different places. It is a flickering starry sky. Now we
have the possibility - we are set up for that - to pull the radium salt a
little bit away from the material while we are watching. We will then see
how the stars diminish. Finally there are none left. And the other way
around: if one brings the radium salt closer to the surface, the flickering
will increase.

Allow me to insert something here. I do not speak out against using
mathematics, nor against a moderate dose of atomic theory in high
school. I have nothing against nurturing abstract intelligence, but I
am against isolating it. I do not speak for a flight into the phenomena,
but I do say that they should have priority. I am advocating for
something, namely for experience, such as I have described here, being
fundamental and remaining so. Of course quiet observation, reflection
and dialogue take time. It is a remarkable thing that one often looks
in vain for the preconditions for such learning in schools."Are those
the atoms?" the over-informed child will ask. No, they are light flashes
(scintillations). But one has the impression that this radium salt sprays
from out of itself highly refined chaff that scratches the surface. It
is not that we have really seen atoms, but we are close. As close as
the tracks of a bird are to an actual bird that landed on the snow for
a moment. This small and cheap peep-box for atoms is of course only a
beginning step in the exploration of radioactivity. The next question
from the child is likely to be, "Will the radium become less now?" Yes,
it will. It won't go quickly, but it can be noticed after many years. Here
one sees: at this point one cannot get around measuring and
calculating anymore.

The examples brought here to illustrate making present and giving priority
to the appearances lie close to the twilight zone of physics, where
physical concepts can no longer be pictured. Here especially phenomena
should be presented unencumbered by instruments wherever possible. They
should make an impression that is hard to forget, no matter how much time
is needed, and students should make these experiences before measurements
are introduced.

Take the pendulum. It is certainly right to take as a starting point the
memories every child has of being on swings. But a small brass ball on a
thin short thread - is that really the same thing? For the scientists it is,
but for the child it will diminish seriousness, because it smacks of
dollhouse days.

Back in the early days of my teaching, I woke up to that one day. So one
afternoon I dragged a chunk of rock as big as a soccer ball into the
school, tied it to a thick rope and suspended it from the ceiling, which
was about 16 feet high. The next day in the physics period I said nothing
at all and only let the heavy pendulum swing into view from the side. How
slowly it goes! Just looking at it has a calming effect. The demonstration
gets the boys and girls out of their seats all by itself. Filled with
respect, they crowd around the area where the pendulum swings. Nothing need
be said. There is no need to arrange anything further in order for them to
get a feel for the phenomenon; all that is needed is time, which schools
are so rarely allowed to take. All heads follow the pendulum's path, back
and forth, from left to right. At first there is the slow start, followed
by the stormy rush through the midpoint - the fall is caught; on the other
side comes the hesitant ascent until the point of return is reached. The
rock doesn't get up as high as it was on the other side. Now the swing we
were familiar with is objectified; we face it. It swings all by itself,
almost effortlessly. No one needs to push; it is quite sure of itself. Just
looking at it reminds us of moderation. This pendulum carries the measure
of its swinging, its very slow swinging, within itself. Why does this long
pendulum swing so slowly? At this point the realization dawns: here's when
the number approaches, the law. The big pendulum evokes questions that
don't arise when looking at the small, hasty one. The first question
concerns the enigmatic highest point where the rock turns around. What
happens at that moment; does it move there or does it not? Does it stop, or
what? How long does that moment, where it doesn't move, last? Once this
question has been seen, a conversation will start with uncertain outcome.
The pupils will seek to understand what happens in the language they have
at their disposal, not yet the language of physics. The teacher does not
need to say anything. Only at the end he might summarize as follows: it has
come to a standstill without duration, what physicists call a "moment." It
is shorter than the blink of an eye, smaller than any moment, below number.
Its duration is zero. A body stands there and yet it doesn't stand still;
there is such a thing.

This introductory consideration does not preclude that we will come to the
formula for pendulum movement. On the contrary, observation reveals the
thing and allows it to speak, while at the same time allowing the students
to be "with it." Haste spoils everything.

Physics Forgettable and Unforgettable

Quiet dialogue with both students and laypeople over the years shows that
for many people a connection to natural phenomena is irrevocably torn. This
begins early on in their schooling and is due to such factors as: entering
too early and too hastily into the realm of quantitative teaching
apparatus; merely copying technical terminology; only applying formulas;
applying all-too tangible models that give rise to misunderstandings. As a
result, students' perception is disturbed rather than enhanced, and their
sensitivity for both phenomena and language is equally diminished.

The result is that many people do not like to remember the physics they
had in school, and their learning disintegrates in no time.

It is worrisome to see how weak the retention is of what pupils learned in
school about physics (close observation indicates that half a year after
the completion of school is enough to let the knowledge dissipate), because
teachers hardly perceive this and therefore do not believe it. If we look
more closely at individual students we see an increase in cases where the
expected knowledge has disintegrated, obscuring the phenomenon, rather than
illuminating it. How else could it happen that about nine out of ten people
witness month after month how the moon changes its luminous shape, yet
believe all their lives that they learned in school (I suspect in a
demonstration with a lamp, an apple and a nut, instead of looking at the
phenomenon in the sky) that this is caused by the shadow of the earth. They
have not once seen the way in which the sun is always positioned close to
the narrow (therefore strongly darkened) sickle of the moon and not
opposite it (the way it ought to be if the sun would project the shadow of
the earth onto the moon.) There are many examples of this kind. Worse than
these individual errors is the fact that many laypeople do not have any
understanding of physics. A comparison presents itself:

In the same way in which a children's hospital, hygienic though it may be,
cannot replace the mother in early childhood, in basic physics education
the natural phenomenon cannot be represented by quantitative laboratory
effects, however exact they may be, and this goes even more strongly for
representing phenomena by means of models.

Physics will appear to the learner other than what it is - not a mindscape
that limits but illuminates, overarching original nature and enriching it,
but rather a subject that throws a shadow over an eerie Natura
denaturata (denatured nature) and makes it desolate. [vii]

Allow me to close with a report by Marie Curie about the time when she and
her husband Pierre Curie had discovered radium. She writes, "we observed
with special joy how our radium-concentrated samples all glowed of their
own accord. We would sometimes come back to the laboratory at night after
dinner to have a look at our kingdom...Our precious products were spread
out on tables and planks; from all sides one saw their dimly glowing
outlines, and these lights, that seemed to float in the darkness, were
always a new occasion for us to be moved and excited." [viii]

This is a condensed version of a longer essay written in German in
1975. It was first published in the journal Der mathematische und
naturwissenschaftliche Unterricht (1977, vol. 30 (3), pp. 129-137). It
was re-published in the book Naturphänomene sehen und
verstehen (by Martin Wagenschein and H. Chr. Berg, Stuttgart:
Klett Verlag, 1980, pp. 90-104) and again in Erinnerungen
für Morgen (by Martin Wagenschein, Weinheim: Beltz, 1983,
pp. 135-153). The latter publication was used for this translation, and
the subheadings were added by us. Translation by Jan Kees Saltet and
Craig Holdrege. Copyright 2008 The Nature Institute. The complete essay
is at:
http://natureinstitute.org/txt/mw/save_phenomena_full.htm.

Notes

[i]. Pestalozzi, J. H. (1949). Sämtliche Briefe vol. 3, p. 147.
Berlin: de Gruyter. Pestalozzi wrote this letter to the tutor Peter
Peterson in the spring of 1782 in Basel.